Increasing voltage to COR on Maxtrac

Haloncloud · Post by **Haloncloud** » Sat Jul 03, 2004 7:27 pm

I was wondering if there is a way to increase the voltage of the COR Pin 8 on a Maxtrac ? It is now 4.5V and I need +5V.

Thanks
Haloncloud

n5tbu · Post by **n5tbu** » Sun Jul 04, 2004 4:05 am

What are you trying to do that .5 volts will make a difference?
mod

Haloncloud · Post by **Haloncloud** » Sun Jul 04, 2004 5:25 am

I’m interfacing to a VA3TO controller for Echolink and I can’t get the COR to work and from what I can tell I need 5V I know it’s not much difference 4.5v to 5v but it does say 5V min.

Haloncloud

Nand · Post by **Nand** » Sun Jul 04, 2004 5:33 am

You can program pin 4 (the alarm output) as COR. Pin 4 when active is pulled to 13 volts and when not active, is presents a 10 Kohm resistor to ground. It can drive a small relay. I believe the maximum current it can handle is 200 mA.

After checking, the above is what I did with my simple EchoLink interface. The COR output on pin 8 cannot drive an opto-isolator because it only is pulled high through a 4.7k resistor in the Maxtrac.

http://www.teepeecomm.com/ilink/V21schem.pdf

Nand.

Haloncloud · Post by **Haloncloud** » Sun Jul 04, 2004 6:41 am

Nand,

Do you think if I built a voltage regulating circuit using a 7805 volt reg. to take my 12V to 5V would this work or would I be better off with the Relay?

Haloncloud

Nand · Post by **Nand** » Sun Jul 04, 2004 8:12 am

You should be able to use the pin 4 output directly going into the interface. The interface has a 1k resistor feeding the opto-isolator. So the current that flows when active is around 10 mA. That is fine.

Nand.

Will · Post by **Will** » Wed Jul 07, 2004 12:10 am

If you need more drive from pin 8, which is pulled up to 5V with a 4.7 k resistor. Put a 1,5 k from pin 8 to pin 13 switched A+ (12V). The transistor can sink the extra current with the added 1.5k resistor.

Post by **wavetar** » Wed Jul 07, 2004 4:38 pm

You can also add a diode in line with the Pin 8 output, adding approx 0.7 volts potential to ground. Had to do it myself for the CM200 series, as they only put out about 3.75 volts.

Todd

jackhackett · Post by **jackhackett** » Wed Jul 07, 2004 6:38 pm

"You can also add a diode in line with the Pin 8 output, adding approx 0.7 volts potential to ground."

Where exactly would you put this diode?

Post by **wavetar** » Thu Jul 08, 2004 7:05 am

jackhackett wrote:"You can also add a diode in line with the Pin 8 output, adding approx 0.7 volts potential to ground."

Where exactly would you put this diode?

"In-line with the Pin 8 output"...

Just like it reads, put a diode somewhere in line with the wire coming out of pin 8. Make sure the polarity is correct, to ensure it passes the DC output. It adds approx 0.7 volts potential to ground.

Todd

jackhackett · Post by **jackhackett** » Thu Jul 08, 2004 10:33 am

Just like it reads, put a diode somewhere in line with the wire coming out of pin 8. Make sure the polarity is correct, to ensure it passes the DC output. It adds approx 0.7 volts potential to ground.

In that case unless the diode has a battery in it, it should subtract 0.7v or so from the output voltage.

If you were using the output to sink current from your load, a diode would give you an extra 0.7 volts when in the low state, but you wouldn't usually want that, you'd want it to go as close to ground as possible.

Haloncloud · Post by **Haloncloud** » Sat Jul 24, 2004 9:15 am

I did as Nand suggested and used Pin 4 programmed (the alarm output) as COR for the COS connection on the VA3TO. Have had Echolink up and down in test mode and has been working great. Hopefully have it up and running full time in the 30days.

Haloncloud
David